ADSORPTIVE STRIPPING VOLTAMMETRY ON MERCURY FILM ELECTRODES IN THE PRESENCE OF SURFACTANTS

The effect of various surfactants on the stripping response for analytes adsorbed on a mercury film electrode (MFE) was studied and compared with the effect observed under identical conditions when a hanging mercury drop electrode (HMDE) was used. It was found that many surfactants interfere severely even at the mg l-1 level and it has been demonstrated that, generally, the in situ-plated MFE is as tolerant as the HMDE to the presence of surfactants. In addition, two simple, inexpensive and efficient methods (one involving addition of fumed silica to the sample and the other coating the electrode with Nafion) for alleviating the problem caused by surfactants in conjunction with MFEs were assessed and compared. As it was found that the addition of fumed silica straight into the aqueous sample solution was not effective, a simple modification of the method was devised and applied with successful results.